"Mrs. Ashton has received an open invitation from Mr. Zarif to travel to Iran at any time she wants," Abbas Araqchi, Iranian deputy Foreign Minister and top nuclear negotiator, was quoted as saying by semi-official Mehr news agency.

Araqchi said that his two-day talks with Helga Schmid, deputy of Catherine Ashton, which concluded on Friday in Geneva "were serious and were carried out in an atmosphere of mutual understanding."

"Solutions for three remaining disagreements have been found, but the capitals should decide on them" before they take effect, said Araqchi.

He added that in case of any rejection of the solutions, Iran and the powers will arrange other meetings for further discussions.

Iran and the EU held a meeting in Geneva on Thursday and Friday to discuss remaining issues pertaining to the implementation of an interim nuclear deal clinched between Tehran and the major world powers in November.

Under the interim nuclear deal, Iran agreed to curb parts of its nuclear program for six months in return for limited relief of western and international sanctions against the country.

Nuclear experts from Iran and the six powers have held three rounds of talks to resolve various technical issues before the Geneva deal can be put into place.